rusteal_codegen/
naming.rs

1// Name conversion utilities for codegen.
2
3/// Convert a PascalCase or UPPER_CASE name to snake_case.
4pub fn to_snake_case(name: &str) -> String {
5    let mut result = String::with_capacity(name.len() + 8);
6    let chars: Vec<char> = name.chars().collect();
7
8    for (i, &ch) in chars.iter().enumerate() {
9        if ch.is_ascii_uppercase() {
10            if i > 0 {
11                let prev = chars[i - 1];
12                // Underscore before an uppercase preceded by a lowercase or digit,
13                // or starting a new word in an acronym ("HTTPServer" -> "http_server").
14                let new_word = prev.is_ascii_lowercase()
15                    || prev.is_ascii_digit()
16                    || (prev.is_ascii_uppercase()
17                        && i + 1 < chars.len()
18                        && chars[i + 1].is_ascii_lowercase());
19                if new_word {
20                    result.push('_');
21                }
22            }
23            result.push(ch.to_ascii_lowercase());
24        } else {
25            result.push(ch);
26        }
27    }
28
29    result
30}
31
32/// Strip the 'b' prefix from boolean property names (e.g., "bNetTemporary" -> "net_temporary").
33pub fn strip_bool_prefix(name: &str) -> String {
34    if name.starts_with('b') && name.len() > 1 && name.as_bytes()[1].is_ascii_uppercase() {
35        to_snake_case(&name[1..])
36    } else {
37        to_snake_case(name)
38    }
39}
40
41const RESERVED_WORDS: &[&str] = &[
42    "as", "break", "const", "continue", "crate", "else", "enum", "extern", "false",
43    "fn", "for", "if", "impl", "in", "let", "loop", "match", "mod", "move",
44    "mut", "pub", "ref", "return", "self", "Self", "static", "struct", "super",
45    "trait", "true", "type", "unsafe", "use", "where", "while", "async",
46    "await", "dyn", "abstract", "become", "box", "do", "final", "macro",
47    "override", "priv", "typeof", "unsized", "virtual", "yield", "try",
48];
49
50/// Check if a name is a Rust reserved word.
51pub fn is_reserved(name: &str) -> bool {
52    RESERVED_WORDS.contains(&name)
53}
54
55/// Escape Rust reserved words by prepending `r#`.
56pub fn escape_reserved(name: &str) -> String {
57    match name {
58        // Keywords a raw identifier cannot be: an underscore keeps them apart
59        // (`EBTFlowAbortMode::Self` is `Self_`).
60        "Self" | "self" | "super" | "crate" => format!("{name}_"),
61        _ if is_reserved(name) => format!("r#{name}"),
62        _ => name.to_string(),
63    }
64}
65
66/// Strip the UE prefix from a class name (A for actors, U for objects).
67/// The JSON `name` field typically already has this stripped, but cpp_name doesn't.
68#[allow(dead_code)]
69pub fn strip_ue_prefix(cpp_name: &str) -> &str {
70    if cpp_name.len() > 1 {
71        let first = cpp_name.as_bytes()[0];
72        let second = cpp_name.as_bytes()[1];
73        if (first == b'A' || first == b'U') && second.is_ascii_uppercase() {
74            return &cpp_name[1..];
75        }
76    }
77    cpp_name
78}
79
80/// Strip the F prefix from struct names.
81#[allow(dead_code)]
82pub fn strip_struct_prefix(cpp_name: &str) -> &str {
83    if cpp_name.len() > 1 && cpp_name.as_bytes()[0] == b'F' && cpp_name.as_bytes()[1].is_ascii_uppercase() {
84        &cpp_name[1..]
85    } else {
86        cpp_name
87    }
88}
89
90/// Convert a UE module/package name to a Rust module name.
91#[allow(dead_code)]
92pub fn to_module_name(name: &str) -> String {
93    // Already snake_case or lowercase is common for module names
94    let snake = to_snake_case(name);
95    escape_reserved(&snake)
96}
97
98#[cfg(test)]
99mod tests {
100    use super::*;
101
102    #[test]
103    fn test_to_snake_case() {
104        assert_eq!(to_snake_case("AActor"), "a_actor");
105        assert_eq!(to_snake_case("GetObjectCount"), "get_object_count");
106        assert_eq!(to_snake_case("bNetTemporary"), "b_net_temporary");
107        assert_eq!(to_snake_case("HTTPServer"), "http_server");
108        assert_eq!(to_snake_case("FVector"), "f_vector");
109        assert_eq!(to_snake_case("ECollisionChannel"), "e_collision_channel");
110        assert_eq!(to_snake_case("URL"), "url");
111        assert_eq!(to_snake_case("K2_GetActorLocation"), "k2_get_actor_location");
112    }
113
114    #[test]
115    fn test_strip_bool_prefix() {
116        assert_eq!(strip_bool_prefix("bNetTemporary"), "net_temporary");
117        assert_eq!(strip_bool_prefix("bHidden"), "hidden");
118        assert_eq!(strip_bool_prefix("boolean"), "boolean"); // no strip
119    }
120
121    #[test]
122    fn test_escape_reserved() {
123        assert_eq!(escape_reserved("Self"), "Self_");
124        assert_eq!(escape_reserved("crate"), "crate_");
125        assert_eq!(escape_reserved("type"), "r#type");
126        assert_eq!(escape_reserved("r#move"), "r#move"); // already escaped? no — "r#move" is not a keyword
127        assert_eq!(escape_reserved("move"), "r#move");
128        assert_eq!(escape_reserved("actor"), "actor");
129    }
130
131    #[test]
132    fn test_strip_ue_prefix() {
133        assert_eq!(strip_ue_prefix("AActor"), "Actor");
134        assert_eq!(strip_ue_prefix("UObject"), "Object");
135        assert_eq!(strip_ue_prefix("FVector"), "FVector"); // F is not stripped here
136    }
137}
rusteal_codegen/naming.rs

rusteal_codegen/
naming.rs
